The success of implant dentistry was vastly improved by the incorporation of osseointegration. Osseointegration was originally discovered by Dr. P. Bränemark in the 1950s and 1960's using titanium implants. Dr. Branemark, an orthopedic surgeon, discovered that when titanium was implanted into bone, the two substances fused safely and securely. This appeared to provide a permanent solution to the old problem of replacing missing teeth with a durable, stable substitute for the original tooth.
However, what has been proven over time is that intimate bony contact with the dental implant is not the only condition for dental implant success. Bony anatomy at the superior aspect of the dental implant where it meets the eventual dental restoration or prosthesis is also very critical for dental implant success. Dental implant art continues to go through many modifications and evolutions in an attempt to maximize dental implant success, including aesthetic factors.
The result of more than a half century of development is a standardized set of implant hardware, and techniques for using that hardware. Dental implants and their accompanying extensions and abutments have a wide range of different shapes and designs. Examples are manufactured by Nobel Biocare, BioMet 3i, Strauman, Zimmer, BioHoizons, Implant Direct, and a number of others. Practitioners in this particular field are well aware of all the aforementioned hardware produced so that no additional elaboration is needed for an understanding of the background of this invention. Primers on implants are cited in the Information Disclosure Statements.
Historically, dental implants were placed in a surgical staged approach (two stages). The first surgical stage consisted of making an incision in the gingival tissue and reflecting the gingival tissue to the buccal and lingual to expose the alveolar bone. An osteotomy (hole to receive the dental implant fixture) would then be created in an increasing diameter stepwise fashion using a dental drill with low speed and high torque. The dental implant fixture (implant) would then be screwed or pressed into the osteotomy and the gingival tissue would be reapproximated and sutured closed.
After a healing period of two to six months, the second stage surgical procedure would be performed at which time a small flap or hole punch would be used to create a hole in the gingival tissue through which a healing collar (healing abutment) would be placed. The gingival tissue would then heal around the healing collar for two to four weeks, at which time the artificial tooth (crown) would be fabricated and placed by screwing or cementing it to the dental implant final abutment.
A key development in the implant art is the anti-rotational connection between the dental implant fixture embedded in the bone at the missing tooth or extraction site and the final abutment (which holds the prosthesis replacing the tooth) fixed to the implant fixture. The basic designs were developed by Niznick, and are disclosed in a plurality of patents originated by that individual. All of these patents are incorporated herein by reference, and cited in the Information Disclosure Statement.
The anti-rotational connection (for final or prosthetic abutments) patented by Niznick is so important in this art that it has become a key hardware standard, so that its absence in modern implant treatment for partially edentulous situations virtually never occurs. Furthermore, the use of these various anti-rotational connectors determine the techniques and procedures that have also become standard in modern implant dentistry. As such, further elaboration is not required.
Anti-rotational connections come in many shapes, including a hexagonal shape (by Zimmer and BioHorizons); a tri-lobed arrangement (Nobel Biocare); and, an octagon (Strauman), as well as a number of others on the market. By preventing rotation between the permanent (or final) abutment holding the crown complex (prosthesis) to the implant fixture, a high degree of stability is achieved.
Because of the reliability provided by such standard procedures and hardware, a great deal of modern implant dentistry can now be directed to aesthetics, and efficiency in conducting the overall replacement process (to prevent unnecessary discomfort to the patient). The overall process steps and armamentarium, from tooth extraction to placement of the final prosthesis at the edentulous site are crucial in that they determine the overall efficiency and pace of the surgical procedure (including patient discomfort), and most importantly the aesthetic characteristics of the final prosthesis and the surrounding anatomy.
More recent developments in the procedures by which dental implants are placed include performing both the first and second stage surgical procedures at one time (single stage implant surgery), and immediate placement of dental implants after tooth extraction. Single stage dental implant surgery can be described as placing the dental implant fixture and healing abutment or collar at the same time. The advantage of this is that the patient only has to go through one surgical procedure, thereby saving time and inconvenience for the patient.
Conventional healing collars were developed to better facilitate the second stage of the surgical process. This includes the insertion of the healing abutment into the implant through partially healed gingiva to guide the contouring of the gingiva. To facilitate this, conventional healing abutments have always been circular in cross section, and have always been rotatable to screw into the implant. This was done to create as little trauma as possible to the partially healed gingiva. The afore-mentioned anti-rotation locking devices would be unnecessary for conventional healing abutments due to the circular shape of the healing abutment and the need to easily slide them past partially healed gingiva to quickly and easily fit into an existing dental implant. In conventional implant dentistry, it is the permentant abutment supporting the crown or prosthesis, that requires the anti-rotational locking devices.
A disadvantage to the single stage surgical procedure is that maturation of the gingival tissue around a conventional circular cross-sectional (in the horizontal plane) healing collar, heals in a non-anatomic shape. This situation can make the placement of the final crown more difficult. As the gingival tissue matures in a non-anatomic shape it is less resilient to the outward pressure of the final crown's (prosthetic tooth) greater overall dimension and different shape, which can cause a mismatch between gingiva and crown. This can hinder the complete seating (cementation) of the final crown.
This situation can cause the crown to be incompletely connected onto the abutment, therefore requiring reduction of the crown's occlusal surface or resulting in open regions between the abutment and crown interface. Open regions between the abutment and crown can cause cement extrusion into the surgical site resulting in an inflammatory tissue response and compromised healing. Both stability and aesthetics can be compromised.
A disadvantage of immediate dental implant placement after tooth extraction is the possibility of initial reduced stability of the implant fixture due to the implant osteotomy not having the same shape as the tooth root socket. To address this, bone graft materials are often placed within the tooth root socket around the dental implant fixture to help bone completely form around the dental implant fixture. With lack of gingival tissue to help retain the bone graft, the graft can become unstable. A conventional circular healing abutment does not allow for complete occlusion of the gingival opening and stabilization of the bone graft.
Membranes made of different materials have been used in the past to attempt to stabilize bone graft materials. However, their lack of rigidity can also lead to bone graft instability. This lack of bone graft stability can lead to loss of the bone graft and non-ideal alveolar bone anatomy. Non-ideal alveolar bone anatomy around a dental implant will ultimately lead to displeasing aesthetic results.
In modern implant dentistry, the aesthetics of dental implants and the surrounding tissue have become paramount. The conventional art regarding healing abutments focuses largely on maintaining a gingival opening for the tooth restoration to traverse through. Conventional healing abutments have been designed with a circular cross sectional configuration so as to create a gingival opening to accept the restoration hardware (crown and holding abutment). Conventionally, there is a wide range of sizes and shapes available that create a circular cross sectional opening within the gingiva. Such systems have only occasionally been successful in contouring gingiva, and providing acceptable final aesthetic results.
Custom made temporary prostheses have also been used but are labor intensive, take multiple appointments, and do not contour, contain, and stabilize bone graft materials. These temporary prostheses are usually fabricated to gradually increase in size with the attempt to contour the gingival tissue over time. This approach can be very time consuming, expensive for the patient, and only addresses the gingival tissue.
History has shown that favorable final aesthetics is directly related to the shape of the gingival anatomy and shape of the interdental gingival papilla. Numerous studies (Tarnow, Salama, and the like) have shown that the final anatomic shape and appearance of the interdental papilla is directly affected by the height of the alveolar crestal bone and its distance from the interproximal contact point of the two adjacent tooth crowns. These studies are incorporated herein by reference.
It has been shown that the distance from the height of the alveolar crestal bone to the contact point can determine whether or not the interdental gingival papilla between the crowns will appear anatomically correct. If the distance between the two landmarks is less than the recommended guidelines, the practitioner can be relatively certain that the interdental papilla will fill the space between the tooth crowns leading to favorable aesthetics. If the distance between the landmarks is greater than the recommended guidelines then the probability for incomplete presence of the interdental papilla increases and esthetics becomes less favorable. However, conventional techniques have proven unreliable in controlling the desired contouring of gingiva.
Accordingly, there exists a need in implant dentistry for an enhanced healing abutment system for bone contouring, containment, and stabilization. An improved healing abutment would facilitate the desired bone shape and aesthetic result. The improved healing abutment system, whether stock or custom fabricated, would contour, contain, and stabilize bone graft material and ultimately facilitate formation of ideal alveolar crestal bone at a tooth extraction site. This creation of ideal alveolar bone anatomy would lead to ideal dental implant aesthetics.